As women have entered the work force in increasing numbers, several dilemmas have developed. Women have assumed greater job responsibility, even as they have attempted to maintain their nurturing, maternal role. Many women who have chosen the dual roles of mother and provider return to the work force before full weaning of their infant has been accomplished.
Meanwhile, the medical profession has continued to advance the beneficial aspects of breast feeding, such as better nutrition and allergy prevention. Ofttimes mothers are encouraged to breast feed their child for a year or longer.
For the working mother, breast feeding poses several difficulties. In order to continue to successfully nurse, the mother must produce or "express" milk while she is apart from her child. She must express milk so as to replenish the supply of milk the infant consumes in her absence. She must produce milk in order to assure that lactation will not diminish due to lessened demand. She must also express milk to avoid physical discomfort. The working mother must then produce, store, chill and transport expressed human milk while in the workplace environment.
In the field of storing, transporting and chilling expressed human milk in the workplace, there are a number of devices which have been utilized. Each of these prior methods and device have multiple drawbacks.
Human milk is an ideal bacterial growth medium. Even though collection bottles and breast pumps are sterilized, bacteria from the skin generally manages to invade the expressed milk. Human milk has a natural bacteriostatic character, but unless the milk is promptly chilled, bacteria can rapidly multiply. Minimizing the temperature of the milk retards bacterial spoilage.
The most frequent practice of chiling and storing expressed human milk is to place the warm milk in the workplace refrigerator. This practice is imperfect for several reasons. A woman may feel that placing her milk in a communal refrigerator is indiscrete. Also the milk is not thoroughly, evenly, or rapidly chilled, since the cool air of the refrigerator is an anemic heat transfer medium. Moreover, freezing the milk in the refrigerator mandates lengthy defrosting before consumption. Finally, many women simply do not have ready access to a refrigerator, either due to the structure of their work environment or because their position entails travel.
Other prior methods and devices have sought to overcome these disadvantages. One method is to deposit the warm expressed milk in containers inside an insulated chest containing ice. This technique provides for very slow chilling, since like a refrigerator, it relies upon cool air alone to lower the milk's temperature. Also the carriers employed in this technique are bulky and difficult to carry. Moreover, these primitive carriers often do not provide for the storage and transportation of necessary equipment, such as a breast pump.
Still another method is to deposit the milk in a plastic bag, which is then packed in an insulated bottle or jar containing crushed ice. While this method allows for direct contact between the bagged milk and the ice, the bags tend to leak. Also, conventional insulated bottles have little interior capacity for both crushed ice and bagged milk. Therefore, the amount of milk which can be stored in such a manner is necessarily small.
A variation on the prior technique is to freeze water in a plastic bottle and place the bottle in an insulated jar. Warm milk is then poured into the jar around the frozen plastic bottle. The disadvantages to this technique are that warm milk from later expressions is mixed with cooled milk from earlier expressions, thereby raising the temperature of the already cooled milk. The potential for bacterial spoilage increases with every deposit of warm milk.
Still another technique is to place ice cubes directly in a heavy insulated bottle. Then at the workplace, the ice cubes are discarded and replaced with warm milk. This method has the same significant undesirable aspect as the prior method since the addition of new milk increases the temperature of the old, making the entire expression more susceptible to spoilage. Furthermore, the insulated bottle does not have sufficient thermal mass to completely cool the expressed milk to an acceptable and safe temperature.